[hab] Allow flexible whitespace in HAB_DOCKER_OPTS
[hab] Allow flexible whitespace in HAB_DOCKER_OPTS

This partially fixes #5115. To fix it completely, we would have to lex
the string to identify quoted whitespace.

But, I think this improves the common case at a rather low cost.

Signed-off-by: Steven Danna <9ce5770b3bb4b2a1d59be2d97e34379cd192299f@chef.io>

rsertelon/habitat,habitat-sh/habitat,habitat-sh/habitat,habitat-sh/habitat,habitat-sh/habitat,rsertelon/habitat,habitat-sh/habitat,habitat-sh/habitat,rsertelon/habitat,rsertelon/habitat,rsertelon/habitat,habitat-sh/habitat,habitat-sh/habitat,rsertelon/habitat,rsertelon/habitat